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Full text of "IS 3025 (Part 02): Method of Sampling and Test (Physical and Chemical) for Water and Wastewater, Part 02: Determination of 33 Elements by Inductively Coupled Plasma Atomic Emission Spectroscopy"

**************** 




Disclosure to Promote the Right To Information 

Whereas the Parliament of India has set out to provide a practical regime of right to 
information for citizens to secure access to information under the control of public authorities, 
in order to promote transparency and accountability in the working of every public authority, 
and whereas the attached publication of the Bureau of Indian Standards is of particular interest 
to the public, particularly disadvantaged communities and those engaged in the pursuit of 
education and knowledge, the attached public safety standard is made available to promote the 
timely dissemination of this information in an accurate manner to the public. 




Mazdoor Kisan Shakti Sangathan 
"The Right to Information, The Right to Live'' 



IS 3025 (Part 02) (2004) : Method of Sampling and Test 
(Physical and Chemical) for Water and Wastewater, Part 02: 
Determination of 33 Elements by Inductively Coupled Plasma 
Atomic Emission Spectroscopy. ICS 13.060.50 




Jawaharlal Nehru 
'Step Out From the Old to the New" 



aj^&Vi ilW^K-^i^^^ T ^bi^ nVF^f 



::^^s^\n%i9^j^/;s^>^^^^ 



K^^^iXSVCd^ 



Satyanarayan Gangaram Pitroda 
Invent a New India Using Knowledge 



Bhartrhari — Nitisatakam 
''Knowledge is such a treasure which cannot be stolen" 




^'^^^r 



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IS 3025 (Part 2) : 2004 
180 11885:1996 

^TFT 2 ^r^uT ^f^ ^=TKFfT 3nfu^ vdc^iHu^H TCjcf^twWt ^RT 33 cR^ flTcT c^^^ 

Indian Standard 

METHODS OF SAMPLING AND TEST (PHYSICAL 
AND CHEMICAL) FOR WATER AND WASTE WATER 

PART 2 DETERMINATION OF 33 ELEMENTS BY INDUCTIVELY COUPLED PLASMA 

ATOMIC EMISSION SPECTROSCOPY 

(First Reprint JUNE 2007) 
ICS 13,060.50 



© BIS 2004 
BUREAU OF INDIAN STANDARDS 

MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG 

NEW DELHI 110002 

June 2004 Price Group 7 



Environment Protection and Waste Management Sectional Committee, CHD 32 



NATIONAL FOREWORD 

This Indian Standard (Part 2) which is identical with ISO 11885 : 1996 'Water quality — Determination 
of 33 elements by inductively coupled plasma atomic emission spectroscopy' issued by the 
International Organization for Standardization (ISO) was adopted by the Bureau of Indian Standards 
on the recommendations of the Environment Protection and Waste Management Sectional Committee 
and approval of the Chemical Division Council. 

The text of ISO standard has been proposed to be approved as suitable for publication as an Indian 
Standard without deviations. Certain conventions are, however, not identical to those used in Indian 
Standards. Attention is particularly drawn to the following: 

a) Wherever the words 'International Standard' appears referring to this standard, they should be read 

as 'Indian Standard', 

b) Comma (J has been used as a decimal marker while in Irdian Standards, the current practice is to use 

a point (.) as the decimal marker. 

CROSS REFERENCES 

In this adopted standard, reference appears to the following International Standard for which Indian 
Standard also exists. The corresponding Indian Standard which is to be substituted in its place is 
given below along with its degree of equivalence for the edition indicated: 

International Standard Corresponding Indian Standard Degree of 

Equivalence 

ISO 5667-3 : 1994 Water quality — IS. 3025 (Part 1) : 1967 Methods of Technically 
Sampling — Part 3 : Guidance on the sapling of test (physical and chemical) equivalent 
preservation and handling of samples for water and wastewater: Part 1 

Sampling (first revision) 



IS 3025 (Part 2) : 2004 
ISO 11885 : 1996 



Indian Standard 

METHODS OF SAMPLING AND TEST (PHYSICAL 
AND CHEMICAL) FOR WATER AND WASTE WATER 

PART 2 DETERMINATIOIM OF 33 ELEMENTS BY INDUCTIVELY COUPLED PLASMA 

ATOMIC EMISSION SPECTROSCOPY 



1 Scope 

1.1 Field of application 

This International Standard specifies a method for the determination of dissolved, particulate or total elements in 
raw, potable and waste water for the following elements: 

aluminium, antimony, arsenic, barium, beryllium, bismuth, boron, cadmium, calcium, chromium, cobalt, copper, 
iron, lead, lithium, magnesium, manganese, molybdenum, nickel, phosphorus, potassium, selenium, silicon, 
silver, sodium, strontium, sulfur, tin, titanium, tungsten, vanadium, zinc, zirconium. 

Table 1 lists these elements along with the recommended wavelengths and typical estimated instrumental detection 
limits using conventional pneumatic nebulization. Actual working detection limits are sample-dependent and as the 
sample matrix varies, these concentrations can also vary. 

Because of the differences between various makes and models of satisfactory instruments, no detailed instrumental 
operating instructions can be provided. Instead, the analyst will need to refer to the Instructions provided by the 
manufacturer of the particular instrument. 

1.2 Interferences ' 

Table 2 lists elements and the most important spectral interferences at the wavelengths recommended for analysis. 

Several types of interference effects can contribute to inaccuracies in the determination of trace elements. They can 
be summarized as follows. 

a) Spectral interferences, categorized as: 

1) overlap of a spectral line from another element; these effects can be compensated by utilizing computer 
correction of the raw data; 

2) unresolved overlap of molecular band spectra; these effects can possibly be overcome by selection of an 
alternative wavelength. 

If the appropriate equipment is available, wavelength scanning can be performed to detect potential spectra! 
interferences. 

b) Background influences, categorized as: 

2) background contribution from continuous or recombination phenomena; 

3) background contribution from stray light from the line emission of elements in high concentration. 

The effect of background interferences can usually be compensated by background correction adjacent to the 
anaiyte line. 



1—92 BIS/ND/07 



IS 3025 (Part 2> : 2004 
ISO 11 885 : 1996 



Table 1 — Recommended wavefeogttis and typical detection limits 



EBem®nt 


Wavelength 


Limit of detection 


EI@ifi®ot 


Wavelength 


Limit of detection 




nm 


mg/1 




nm 


mg/! 


Ag 


328,068 


0,02 


Mo 


202.030 


0,03 




338,289 


0,02 




204,598 


0.05 


M 


308.215 


0,1 


Na 


589,592 


0,1 




396.152 


0,1 




588,995 


0,02 




167.08 


0.04 




330.237 


0.02 


As 


193,696 

197.197 


0,1 
0,1 


. Ni 


231,604 






189,042 


0,08 


P 


178,287 
213,618 


0,5 
0,1 


B 


208,959 


0,005 




214,914 


0.1 




249,678 


0.006 




177,428 


0,5 




247,773 


0.01 














Pb 


220,353 


0,2 


Ba 


233,527 
455,403 


0,004 
0,002 




283,306 


0.07 




493,409 


0,003 . 


S 


182,036 


0.5 




313,042 


0,002 




180,669 


0.5 




234.861 


0,005 










313:107 




Sb 


206,833 
217.581 


0,1 

0,1 * , 


Bi 


223,061 


0,04 










306.772 


0.08 


Se 


196,026 
203.985 


0,1 
0,1 


Ca 


315,887 


0,1 










317.933 


0,01 


Si 


251,611 


0,02 




393,366 


0.002 




212,412 
288.158 


0,02 
0,03 


Cd 


214,438 


0.01 










226,502 


0,01 


Sn 


235,848 


0,1 




228.802 


0.01 




189,980 


0.1 


Co 


228.616 


0.01 


Sr 


407,771 
421.552 


0.0005 
0.01 


Cr 


205.552 

267.7 1> 


0,01 
0,01 




460,733 


0,1 




283,563 


0,01 


Ti 


334,941 


0,005 




284,325 . 


0,01 




336,121 
337.280 


0,01 
0,01 


Cu 


324,754 
327,396 


0,01 
0.01 




368,520 


0,01 








V 


290,882 


0.01 


Fe 


259.940 


0,02 




292.402 


0,01 




238.20 






310.230 
311,071 


0,01 
0.01 


K 


766,490 












769,90 


2 


W 


207,9lV 
209.860 


0,03 
0,06 


Li 


460,286 


0,9 




239,709 


0,06 




670,784 


0,002 




222,589 
202,998 


0,06 
0.06 


Mg 


279.079 


0.03 










279,553 


0.0005 


In 


206.191 


0,01 




285,213 


0.001 




213.856 


0.005 


Mn 


257,610 


0.002 


Zr 


343,823 


0,01 




293,306 

■ ' ■ 


0,02 




354,262 
339 J 98 


0,05 



IS 3025 {Part 2) : 2004 
ISO 11885 : 1996 



Table 2 — Spectral Interfereriees 



Element 


Wavelangth 


interfering 


Element 


Wavelength 


Interfermn 




nm 


eleinants 




nm 


eienients 


Ag 


328,068 




Mo 


202,030 


Al, Fe 




338,289 


Cr 




204.598 




A! 


308,215 


Mn, V, Fe 


Na 


589,592 


Ar 




396,152 


Mo, Cu 




588,995 






167,08 


Fe 




330.237 




As 


193,696 

197.197 


Fe, A! 
Fe, A! 


Ni 


231,604 


Co 




189,042 


Al 


P 


178.287 
213.618 


1 

Cu, Fe, Mo. Zn 


B 


208.959 


■ Al, Mo 




214.914 


Cu, Al. Mg 




249,678 


Fe, Cr 




177.428 


Cu 




247,773 


Fe 














Pb 


220,353 


Al. Co, Ti 


Ba 


233,527 
455.403 


Fe, V 




283,306 






493.409 




S 


182,036 


Cr. Mo 




313.042 


V 




180,669 


Ca 




234,861 


Fe 










313,107 




Sb 


206,833 
217.581 


Cr. Mg, Co, Mn 


Bi 


223,061 


Cu 










306,772 


Fe. V 


Se 


196,026 
203,985 




Ca 


315,887 


Co 










317,933 


Fe, V 


Si 


251.611 






393.366 






212,412 
288,158 




Cd 


214,438 


Fe 










226,502 


Fe 


Sn 


235,848 


Mo, Co 




228,802 


As, Co 




189,980 




Co 


228,616 


Ti 


Sr 


407.771 
421,552 


/ 


Cr 


205,552 
267,716 


Fe. Mo 
Mn. V 




460,733 






283,563 


Fe. Mo 


Ti 


334,941 


Ca, Cr, Si 




284,325 


Fe 




336.121 
337,280 




Cu 


324,754 
327,396 


Ti, Fe 




368,520 


Co, Cr 








V 


290,882 


Fe, Mo 


Fe 


259,940 






292,402 


Fe, Mo. Cr 




238,20 


Co 




310,230 
311,071 


Fe,Mn,Ti,Cr 


K 


766,490 


Mg, Ar 










769,90 




W 


207,911 
209.860 




Li 


460,286 


Fe 




239,709 






670,784 






222,589 
202,998 


Cu 


Mg 


279,079 












279.553 




Zn 


206.191 


Cr 




285.213 


Fe 




213,856 


Cu. Ni. Fe 


Mn 


257,610 


Fe, Mo, Cr 


Zr 


343,823 






293,306 


A!, Fe 




354,262 
339,198 





IS 3025 IPart 2) : 2004 
ISO 11885 : 1996 

Physical Interferences are generally considered to be effects associated with the sample nebulization and transport 
processes. Such properties as change in viscosity and surface tension can cause significant inaccuracies, 
especially in samples which may contain high concentrations of dissolved solids and/or acid. If these types of 
interference are operative, they will be reduced by dilution of the sample and/or utilization of standard addition 
techniques. 

Chemical interferences are characterized by molecular compound formation, ionization effects and solute 
vaporization effects. These effects are overcome by buffering of the sample matrix and by standard addition 
procedures (see 8.1.3.2). 

Whenever a new or unusual sample matrix is encountered, a series of tests should be performed prior to reporting 
concentration data for analyte elements. When investigating a new sample matrix, comparison tests can be 
performed using other analytical techniques, such as atomic absorption spectrometry'. 

Serial dilution — If the analyte concentration \$ sufficiently high (minimally 10 x the instrumental detection limit after 
dilution), an analysis of a dilution needs to agree within 5 % of the original determination (or within some 
acceptable control limit that has been established for that matrix). If not, a chemical or physical interference effect 
could be responsible. 

Calibration by standard addition (see 8.1.3.2) — A spike added to the original determination at a minimum level of 
10 X the instrumental detection limit (maximum 100 x) needs to be recovered to within 90 % to 1 10 %, or within the 
established control limit for that matrix. If not, a matrix effect should be suspected. The use of a standard addition 
analysis procedure can usually compensate for this effect. 

2 Normative reference 

The following standard contains provisions which, through reference in this text, constitute provisions of this 
International Standard. At the time of publication, the edition indicated was valid. All standards are subject to 
revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying 
the most recent edition of the standard indicated below. Members of lEC and ISO maintain registers of Currently 
valid International Standards. 

ISO 5667-3: 1 994, Water quality — Sampling — Part 3: Guidance on the preservation and handling of samples. 

3 Defiriitions 

For the purposes of this International Standard, the following definitions apply: 

3 J dissolved metals: 

Those metals in a water sample which will pass through a 0,45 )im membrane filter. 

3.2 particulate metals: 

Those metals in a water sample which are retained by a 0,45 )im membrane filter. 

3.3 total metals: 

Concentration of metals determined on an unfiltered sample following digestion (see 8.1.3), or the sum of the 
dissolved (see 8.1.1) plus particulate metal concentrations (see 8.1.2). 

3.4 Instrumental detection limit: 

Concentration, equivalent to a signal due to the analyte. which Is equal to three times the standard deviation of a 
series of ten replicate measurements of a reagent bl^nk signal at the same wavelength. 

3.5 sensitivity: 

Slope of the curve of the relationship between signal emission intensity and sample concentration. 

3.S Instrument check standard: 

Multielement standard of known concentrations prepared by the analyst to monitor and verify instrument 

performance on a dally basis (see 5.7). 



IS 3025 (Part 2) : 2004 
ISO 11885 : 1996 

3 J interfererice check sample: 

Solution containing both interfering and analyte elements of known concentration that can be used to verify 

background and interelement correction factors. 

3.8 liidependent calibration check: 

Solution, obtained from an outside source, having known concentration values to be used to verify the calibration 

standards. 

3J reference standards: 

Series of known standard solutions used by the analyst for calibration of the instrument (i.e. preparation of the 

calibration curve). 

3.10 linear dynamic ranga: 

Concentration range over which the analytical response remains linear. 

3.11 reagent blank: 

Deionized water, containing the same acid matrix as the calibration standards, which is earned through the entire 
analytical scheme. 

3.12 cafsbralioii blank: 

Deionized water acidified with nitric or hydrochloric acid. 

. 3J3 method of standard additloii: 
Analytical technique involving the use of the unknown analyte and the unknown ^nalyte plus a known amount of 

standard analyte (see 8.1.3.2). 

3 J4 sample dypiication: 

Analysis of two portions of the same sample. 

4 Principle 

The basis of the method is the measurement of atomic emission by an optical spectroscopic technique. Samples 
are nebulized and the aerosol that is produced is transported to the plasma torch where excitation occurs. 
Characteristic atomic-iine emission spectra are produced by a radio-frequency inductively coupled plasma (fCP). 
The spectra are dispersed by a grating spectrometer and the intensities of the lines are monitored by detectors. 
The signals from the detectors are processed and controlled by a computer system. A background correction 
technique is used to compensate for variable background contributions to the determination of trace elements. 

5 Reagents 

WARNING — The toxicity of each reagent used in this method has not been precisely defined; however, 
each chemical compound needs to be treated as a potentiaf health hazard. From this viewpoint, exposure 
to these chennieals to the lowest possible level by whatever means available Is recommended. 

Preparation methods Jnvolve the use of strong acids, which are corrosive and cause burns. Laboratory 
coats, gloves and safety spectacles should be worn when haodimg acids. 

Toxic fumes are evolved. by nitric acid. Always carry out digestion In a fume cupboard, as well as addition 
of acid to samples becays© of the possibility of toxic gases being released. 

Tha exhaust gases from the plasma should be ducted away by an efficient fume extraction system. 

SJ General requirerfients 

NOTE — Standard stock solutions may be purchased or prepared from ultrahigh-purity grade chemicals. 

The content of the determinants in the water and reagents shall be negligibly .low, compared wKh the 
concentrations to be determined. - . 



2—92 BiS/ISID/07 



IS 3025 (Part 2) : 2004 

ISO il885 : 1996 

All salts shai! be dried for 1 h at 105 °C unless otherwise specified. 

5.2 Nftricacid, p{HN03) = 1,40g/ml 

5„3 Dihydrogen dioxide (hydrogen peroxide), H^O^, volume fraction 30 %. 

NOTE — On the determination of phosphorus, attention should be paid to a possible stabilization of hydrogen peroxide with 
phosphoric acid, as thss will affect the phosphorous determination. 

5„4 Sulfwc add, p(H,SOJ - .1 ,84 g/ml. 

S3 Hydrochloric acid, c(HCI) :r 0,2 mol/L 

5.6 Ammonium sulfate, (NHJ^SO,. 

5.7 Element stock sofytlons 

Ag, Al, As, B, Ba, Be. Bi, Ca. Cd, Co, Cr, Cu, Fe, K. Li, Mg, Mn, Mo, Na, HI, P, Pb, S, Sb, Se, Si, Sn, Sr, Ti, V, W 
and Zn at mass concentrations of 1 000 mg/! each, 

NOTE — ICP-AES element standard reference solutions with respective specifications which can be used as stock solutions 
are commercially available. They have been prepared according to particusar? of the manufacturer. Nonnaily, these stock 
solutions contain hydrochloric acid or nitric acid and have a shelf life of several months; Formulations for the preparation of 
element stock solutions are identified below. 

5.8 Intermediate mixed standard solutions 

Prepare these as mixed element standards in 5 % nitric acid or 5 % hydrochloric acid (volume fraction). To ensure 

chemical compatibility use the combinations given in 5.8,1 to 5,.8,6. 

On composing multielement reference' solutions, the chemical compatibility and the possible hydrolysis of the initial 
compounds, a3 well as spectral interferences, shall be taken into account. In order to avoid interferences, the 
digestion reagents (e.g. nitric acid, sulfuric acid, aqua regia) shall be added !o the reference solutions, 

SMA yyftiefement reference solution i . 

p(Al, Be, Cd, Co, Cu, Fe, Pb. Li, Mn, Mo. Ni, V, Zn. Bi, Si, Sr, W and Zr) == 10 mg/l. 

■ Prepare this solution by adding (10 ± 0,1) ml of each of the commercial 1 000 mg/l stock standard solutions (5,7) of 
reference 1 elements in a 1 -litre volumetric flask.. 

Add 50 ml of nitric acid (5.2). 

Make up to the volume with water 

6.8,2 Myftielement refereoce solyfion it. , 
p(Sn, Ti, As, Se, Sb) =10mg/L 

Prepare this solution by adding (10 ± 0,1) ml of each of the commercial 1 000 mg/l stock standard solutions (6.7) of 
reference I! elements in a 1 -litre volumetric flask. 

Add 50 ml of nitric acid (5.2). 

Make up to the volume with water 

5 JJ Element reference solution III 

p(Ba)^^10mg/i. 

.Proceed as given in 5.8.2 using (10 ± 0,1) ml of the commercial 1 000 mg/l stock standard solution of barium. ■ 



IS 3025 |Part2> : 2004 
ISO 11885 : 1996 

5.B.4 Element reference solution i¥. 

p(Ag)^ lOmg/!. 

Proceed as given in 5.8.2 using (10 ± 0,1) m! of the commercia! 1 000 mg/! stock standard solution of silver. 

5J.5 Element reference solution V 

p(B)^ 10mg/I, 

Proceed as given in 5.8.2 using (10 ± 0,1) ml of the 1 000 mg/1 stock standard solution of boron. 

Prepare this standard in polymethylpentene (PMP) flasks. 

NOTE — Element reference solutions HI, IV, V, i.e. Ba, Ag, B, are known to cause problems by precipitation under certain 
circumstances, and it is recommended that separate standard solutions are prepared. 

5.3.6 Multielement reference solution Vf 
p (Ca, Mg, Na, K, S, P) = 10 mg/1. 

Prepare this solution by adding (10 ±0,1) ml of each of the commercia! 1 000 mg/l stock solutions (5.7) of 
reference VI elements in a 1 -litre volumetric flask. . 

Add 10 ml of nitric acid (5.2).^ 

Make up to ths volume with water. 

5,9 Reagent blank solution 

Place 1 ml of nitric acid (5.2) and 100 ml of wafer into a polyethylene or polytetrafluorethylene (PTFE) container. 

g Apparatus 

NOTE -" Because of the differences between various makes and models of satisfactory instruments, no detailed operating 
instnictions can be provided. 

6.1 Indoctivefy coupled plasma-atomlc emission spectrometer, including: 

^ computer-controlled atomic emission spectrometer with background correction; 

— radiofrequency generator; 

— argon gas supply (welding grade or better). ' 

6.2 Sample bottles, 250 ml or 500 ml plastics (such as high density polyethylene or PTFE), for sample collection 
and storage. Containers shall have been previously cleaned with 10 % volume fraction nitric add before use. 

8.3 Glassware (beakers, filter funnels, volumetric flasks and pipettes) reserved for element preparation only. All 
glassware shall be soaked in 10 % volume fraction nitric acid overnight before use. 

6.4 Acid dispensers, variable volume. 

6.5 Membrane filtration equipment and filters of pore size 0,45 jim reserved for element preparation, 



IS 3025 (Pan 2} : 2004 
ISO 11885 : 1996 

7 Sample handling and preservation 

7.1 General 

The requirements in ISO 5667-3 apply. 

For the determination of trace elements, contamination and the loss of elements of interest are of prime concern. 
Dust In the laboratory environment, impurities in reagents and impurities on laboratory apparatus which the sample 
contacts are all sources of potential contamination. Sample containers can introduce either positive or negative 
errors in the measurement of trace elements by 

a) leaching or surface desorption, and 

b) by depleting concentrations through adsorption. 

Laboratory glassware, including sample bottles, shall be rinsed before use with nitnc acid folloyved by deionized 
water. 

Perform the following preservation and pretreatment steps (filtration and acid preservation) at the time the sample is 
collected, or as soon as possible thereafter. 

7.2 Prior t© determination of dissolved elemerits 

Filter the sample through a 0,45 (im membrane filter (6.3.2) as soon as possible after collection (glass or PIPE 
filtering apparatus are recommended to avoid'possible contamination). 

Use the first 50 ml to 100 ml to rinse the filter flask. Discard this .portion and collect the required volume of filtrate. 
Acidify the filtrate with 0,5 ml of nitric acid (5.2) per 100 ml of sample to ensure that the pH of the sample is < 2. 

7»3 Prior to determination of particulate elements 

Filter a measured volume of unpreserved sample through a 0,45 jim membrane filter as soon as possible after 
collection. Transfer the filter containing particulate material \o a container for storage and/or shipment. No 
preservative is required. 

7.4 Prior to determination of total elements 

Acidify the sample with 0,5 ml HNO3 (5.2) per 100 ml sample to pH < 2 as soon as possible, preferably at the time of 
collection. Do not filter the sample before processing. 

8 Instrumental method and analytical procedure 
8J Instrumental method 

8,1.1 General. 

Follow the instructions provided by the manufacturer of the particular instrument. 

NOTE— Sensitivity, instrumental detection limit, precision, linear dynamic range and interference effects should be 
investigated and established for each individual analyte line on that particular instrument. 

Set up the instrument with the proper operating parameters established from the manufacturer's instruction manual. 
Allow the instrument to become thermally stable before beginning. 

Initiate the appropriate operating configuration of the computer. 

Profile and calibrate the instrument according to the instrument manufacturer's recommended procedures, using the 
typical mixed calibration standard solutions (5.8.1 to 5.8.6). Flush the system with the reagent blank (5.8.7) between 
■ each standard. 

a 



IS 3025 (Part 2} : 2004 
ISO 11885 : 1996 

Before beginning the sample run, reanaiyse the highest-concentration mixed reference standard as if if were a 
sample. Ensure that the concentration values do not deviate from the actual values by more than ± 5 % (or the 
established control limits, whichever is lower). If they do, follow the recommendations gf the instrument 
manufacturer to correct for this condition- 
Begin the sample run by flushing the system with the reagent blank (5.8.7) solution and flush again between each 
sample. Analyse the instrument check standard (8.1 .2) and the calibration blank ev^ry 1 samples. 

8/1.2 Instrument performance check procedyres 

Analyse an appropnate instrument check standard containing the elements of interest with each batch o^ 
10 samples. This check standard is used to determine instrument drift. If agreement is not within ±5% of the 
expected values or within the established control lim.its, whichever is lower, the analysis is out of control. Terminate 
the analysis, correct the problem, and recalibrate the instrument. 

Analyse the reference standard wfth each batch of 10 samples. The result shall be within the established control 
limits of two standard deviations of the mean value. If not, repeat the analysts two more times and average the three 

results. If the average is not within the control limit, terminate the analysis, correct the problem and recalibrate the 
instrument. 

To venfy intereiement and background correction factors, analyse the Instrument check standard at the beginning, 
end and at periodic inten/a(s throughout the sample run. Results should fall within the established control limits of 
2,0 times the standard deviation of the mean value. If not, terminate the analysis, correct the problem and 

recalibrate the instrument. 

8.1.3 Independent calibration check 

8.1.3.1 General requirement 

An independent calibration standard obtained from an outside source shall first be used for the initial verification of 
the calibration standards. A fresh dilution of this sample shall be analysed every week thereafter to monitor their 
stability. If the results are not within ± 5 % of the true value listed for the control sample, prepare a new calibration 
standard and recalibrate the instrument. If this does not correct the problem, prepare a new stock standard and a 
new calibration standard and repeat the calibration. 

Prepare calibration check standards for all elements from stock solutions resen/ed for this purpose consisting of the 
same matnx as the unknown samples and carried through the entire analytical process. 

Analyse one calibration standard and one blank solution with each batch of 25 samples and take them through the 
entire analytical processes (including dilution, filtering and digestion, etc.). 

8.1.3.2 Standard addition method ©f analysis 

NOTE — The standard addition technique involves preparing new standards in the sample matrix by adding known amounts 
of standard to one or more aliquots of the processed sample solution. This technique compensates for a sample constituent 
that enhances or depresses the analyte signal, thus producing a different slope from that of the calibration standards. It will not 
correct for additive interference. The simplest version of this technique is the single-addition method. 

Take two identical aliquots of the sample solution, each of volume V^. To the first (labelled A) add a small volume Vg 
of a standard analyte solution of concentration p^ of the solvent. Measure the analytical signals of A and B and 
correct for nonanalyte signals. Calculate the unknown sample concentration p^ as follows: 

-^B ■ ^s Ps 

where 

S^, Sq are the analytical signals (corrected for the blank) of solutions A and B, respectively; 

^3 is the added volume of standard analyte, in millilitres; 

\/, is the volume of identical aliquots of sample solution. In millilitres; 

Ps is the mass concentration of standard analyte solution, in milligrams per litre. 



IS 3025 (Part 2) : 2004 
ISO 11885 : 1996 

Choose V^ and p^ so that S^ is on average twice Sg. It is best if V^ is made much less than V^ and thus pg is much 
greater than p^, to avoid excess dilution of the sample matrix. If a separation or concentration step is used, first 
make the addition and carry out the entire procedure. For the results from this technique to be valid, all of the 
following requirements shall apply: 

— the analytical response shall be linear; 

™- the chemical form of the analyte added shall respond the same as the analyte in the sample; 

— the interarence effect shall be constant over the working range of concern; 

— the signal shall be corrected for any additive interference. 
8.2 Analytical procedure 

8,2.1 Determination of dissolved elements 

Analyse^'the filtered, preserved sample (7.2) as-received in accordance with 8.1.1. The acid matrix and 
concentration of the samples and calibration standards shall be the same. It a precipitate has formed upon 
acidification of the sample or during transit or storage, it shall be redissolved before analysis by adding additional 
acid and/or by heating on a hot plate. 

S»2.2 ' Determination of particulate elements 

Transfer the membrane filter containing the insoluble material (see 7.3) to a glass beaker and add 4 ml of nitric acid 
(5.2). Cover the beaker with a watch glass and heat gently. The warm acid will soon dissolve the membrane. 

Increase the temperature of the hot plate and digest the material. When the acid has nearly evaporated, coo! the 
beaker and watch glass and add another 3 ml of nitric acid (5.2). Cover and continue heating until the digestion is 
complete, generally indicated by a light-coloured digestate. Evaporate to near dryness (2 ml), cool, add 10 ml of 
hydrochloric acid (0,2 mol/l) and 15 ml of deionized, distilled water per 100 ml dilution and warm the beaker gently 
for 15 min to dissolve any precipitated or residue material. Allow to cool, wash down the watch glass and beaker 
walls with deionized or distilled water and filter the sample to remove insoluble material which can block the 
nebulizer. Adjust the volume based on the expected concentrations of elements present. This volume will vary 
depending on the elements to be determined. Analyse the sample in accordance with 8.1.1. Concentrations so 
determined shall be reported as "particulate". 

NOTES 

1 Instead of filtering, the sample after diluting and mixing may be centrifuged or allowed to settle by gravity overnight to 
remove insoluble material. 

2 Calibration standards/Analytical Quality Control sotutk)ns should be prepared at the same acid concentration. 

3 A filter blank should be taken through the identical procedure as samples and subtracted from the sample analytical results 
at the calculation stage. 

8.2.3 Determination of total elements 

Acidify 100 ml of sample (see 7.4) with 0,5 ml of nitric acid (5.2). 

Evaporate the mixture to near dryness, making sure that no area at the bottom of the beaker goes dry (a complete 
drying may lead to low results). 

In case of an incomplete digestion (undissolved material), add some water and repeat the treatment. 

Dissolve the residue in 1 ml of nitric acid (5 2) and some water and make up to 100 ml volume with water. Analyse 
the resulting solution in accordance with 8.1.1. 

NOTE ■— Some elements or their compounds (e.g. antimony, silicon, alumina, tin. titanium) are only partially dissolved by this 
digestion procedure and care should be taken in the interpretation of results. 



10 



IS 3025 |Part.2l : 2004 
ISO 11885 : 1996 



9 Calcylatiori and expressiori of resyfts 



Subtract reagent blanks from alt samples. This is particularly important for digested samples requiring large 
quantities of acids to complete the digestion. 

If dilutions were performed, apply the appropriate factor to the sample values. 

Report results in milligrams (or micrograms) of element per litre of sample and up to three significant figures. 

10 Precision 

Typical performance characteristics for precision and accuracy are shown in Table 3. 

Details of an interlaboratory test on the precision of the method are summarized in annex A. The values derived 
from this interlaboratory test may not be applicable to concentration ranges and nr\atrices other than those given. 

11 Test report 

The test report shall contain the following information: 

a) a reference to this International Standard; 

b) a reference to the method used; 

c) complete identification of the sample; 

d) the results of the determinations; 

e) any details not specified in this international Standard or which are optional, as well as any factors which may 
have affected the results. 



11 



iS 3025 {Part 2» : 2004 
ISO 11885 : 1936 



t 


Table 3 ~ Typical precision and accuracy data- 




Element 


True value 


^ — — — 

Mean reported ¥aiye 
/ig/l 


RSD = Vc 


Alunninium 


50 

■ 


51,B 


4.3 


Banum 


2 500 


2 450 


3,8 


Beryllium 


500 


488 


3,1 


Boron 


500 


490 


3.5 


Cadmium 


50 


51.0 ^ 


2.8 


Calcium 


2 000 


20 878 


6,0. 


Chromium 


50 


50.3 


■ 3.3 


Copper 


50 


49,6 . 


5.1 


Iron 


50 


50.5 


5,0 


Lead 


100 


101,4 


2.6 


Magnesium 


2 000 


2 103 


6,0 


Manganese 


50 


49.9 


2,7 


Nickel 


50 


51,6 


3,3 


Phosphorus 


5 000 


4 923 


1.7 


Potassium 


1000 


1 000 


10,6 


Sodium 


2 000 


2 035 


9.7 


Sulfur 


20 000 


19 988 


5.1 


Titanium 


500 


491 


4,2 


Vanadium 


500 


510 


6,3 


Zinc 


50 


49,0 


5.4 



12 



IS 3025 (Part 21 : 2004 
ISO 11885 : 1996 



Annex A 

(informative) 

Results of an interlaboratory trial 



A national interlaboratory trial was performed in January 1 987 in order to compare the repeatability and the 
reproducibility of the methods. These results are summarized in table A.I . 

Table A.I — Statistical characteristics of the method — Standard solutions 



Paramater 


Element j 




B 


Ca 


Cd . 


Gu 


Fe 


Mg 


Mn 


Mo 


Na 


P 


Se 


Ti 


V 


Zn 


No. participating 
laboratories 


23 


25 


21 


24 


26 


25 


19 


22 


21 


20 


21 


22 


23 


24 


No. measuring 
values 


83 


90 


72 


91 


95 


91 


69 


80 


80 


75 


76 


81 


87 


90 


Reference values 

(mg/l) 


3.5 


34.5 


0.1 


0,7 


2,5 


25,0 


0,25 


0.5 


15.0 


6,52 


9.0 


5,5 


0,5 


1,3 


Mean (mg/l) 


3,5 


34,86 


0.098 


0.670 


2,548 


24,93 


0,241 


0,494 


15,07 


6,820 


8.931 


5,449 


0.495 


1,302 


Repeatability: 






























Standard 
deviation Cj 


0,058 


0,817 


0.003 


0,012 


0,045 


0,391 


0,003 


0,017 


0.331 


0.210 


0.177 


0,086 


0.017 


0.024 


Coefficient of 
variation CV, 


1,6 


2.3 


2,9 


1.8 


1.8 


1,6 


1.4 


3,3 


2,2 


3,1 


2.0 


1.6 


3.5 


1.8 


Heproducibility: 






























Standard 
deviation orp 


0.176 


2,112 


0.004 


0.034 


0.118 


0,766 


0,007 


0,026 


0,857 


0,374 


0,474 


0,247 


0,039 


0.068 


Coefficient of 
variation CVp, 


5,0 


6,1 


4,5 


5.1 


4.6 


3,1 


2,7 


5,2 


5,7 


5,5 


4,2 


4,5 


7.9 


4,5 


% Recovery 


100 


101,1 


97,7 


95.7 


101,9 


99,7 


96,5 


98,8 


100,5 


100.4 


99,2 


99.1 


99,0 


100,1 



13 



3—92 BIS/ND/07 



GMGIPN"-92 B1S/HD/07~»^-300